Manually-operated staplers typically include a base that supports a stationary anvil. The anvil is configured to receive and clinch the legs of a staple after passing through the sheets being stapled.
Prior art stationary anvils are commonly designed to accommodate a single size of staple used in the specific stapler on which the anvil is mounted. A typical stapler is capable of successfully fastening together a predetermined range of total sheets. For example, many light-use, desktop staplers accommodate a single size of staple and will staple from two to about twenty sheets successfully. Attempts to staple more sheets will often be unsuccessful because the staple legs are not long enough to accommodate more than about twenty sheets.
Larger, heavy-duty staplers use longer staples designed to staple more sheets. The anvils of heavy-duty staplers are designed to clinch staple legs that have passed through a relatively large number of sheets. Attempts to staple only a relatively small number of sheets (e.g., about twenty sheets) with a heavy-duty stapler will often be unsuccessful because the long legs of the staple will hit one another, jam, and prevent the staple from being completely driven by the stapler. To eliminate or reduce the occurrence of jamming when stapling larger numbers of sheets, the user is required to manually change the staple sizes for different stapling jobs.